MD Settings: Display: Add mirroring and other fixes

chrome/browser/resources/settings/device_page/layout_behavior.js

Index: chrome/browser/resources/settings/device_page/layout_behavior.js
diff --git a/chrome/browser/resources/settings/device_page/layout_behavior.js b/chrome/browser/resources/settings/device_page/layout_behavior.js
index 51ba51bd83342f9380b855e19f5a23c19e4c0dcc..699be738b81f7ba687d65d0c8c20e3f89a10d9f3 100644
--- a/chrome/browser/resources/settings/device_page/layout_behavior.js
+++ b/chrome/browser/resources/settings/device_page/layout_behavior.js
@@ -15,6 +15,12 @@ var LayoutBehavior = {
      * @type {!Array<!chrome.system.display.DisplayLayout>}
      */
     layouts: Array,
+
+    /**
+     * Whether or not mirroring is enabled.
+     * @type {boolean}
+     */
+    mirroring: false,
   },
 
   /** @private {!Map<string, chrome.system.display.Bounds>} */
@@ -49,6 +55,8 @@ var LayoutBehavior = {
     this.dragLayoutId = '';
     this.dragParentId_ = '';
 
+    this.mirroring = displays.length > 0 && !!displays[0].mirroringSourceId;
+
     this.displayBoundsMap_.clear();
     for (let display of displays)
       this.displayBoundsMap_.set(display.id, display.bounds);
@@ -182,11 +190,12 @@ var LayoutBehavior = {
 
   /**
    * @param {string} displayId
+   * @param {boolean=} opt_test

[michaelpg, 2016/07/11 20:41:56]

i'd prefer optional params default to false, e.g. opt_allowMissingBounds

if you insist on opt_test, comment that it asserts by default

[stevenjb, 2016/07/11 21:56:23]

I inverted the variable to be notest instead. We call this about 20 times so I
don't want to pass true explicitly in all of them.

    * @return {!chrome.system.display.Bounds} bounds
    */
-  getCalculatedDisplayBounds: function(displayId) {
+  getCalculatedDisplayBounds: function(displayId, opt_test) {
     var bounds = this.calculatedBoundsMap_.get(displayId);
-    assert(bounds);
+    assert(opt_test === false || bounds);
     return bounds;
   },
 
@@ -308,7 +317,7 @@ var LayoutBehavior = {
   calculateBounds_: function(id, width, height) {
     var left, top;
     var layout = this.displayLayoutMap_.get(id);
-    if (!layout || !layout.parentId) {
+    if (this.mirroring || !layout || !layout.parentId) {
       left = -width / 2;
       top = -height / 2;
     } else {